What is the management approach for a patient with suspected subacute appendicitis presenting with abdominal pain, fever, nausea, vomiting, and loss of appetite?

Management of Subacute Appendicitis

For a patient presenting with abdominal pain, fever, nausea, vomiting, and loss of appetite concerning for subacute appendicitis, obtain CT abdomen and pelvis with IV contrast immediately to confirm diagnosis and assess for complications, then proceed with appendectomy as the definitive treatment. 1, 2

Immediate Diagnostic Workup

Clinical Risk Stratification

• Apply validated clinical scoring systems (AIR score or AAS score in adults, Pediatric Appendicitis Score in children) combining symptoms, physical examination findings, and laboratory values to stratify risk 2, 3, 4
• Document specific peritoneal signs: rebound tenderness, guarding, McBurney point tenderness, psoas sign, obturator sign, and Rovsing sign 2, 3
• The constellation of characteristic right lower quadrant pain, localized tenderness, and laboratory evidence of acute inflammation identifies most patients with appendicitis 1

Laboratory Testing

• Obtain WBC with differential and CRP immediately 2, 4
• The combination of WBC >10,000/mm³ AND CRP ≥8 mg/L has a positive likelihood ratio of 23.32 for appendicitis 2
• Both elevated WBC and left shift together have a positive likelihood ratio of 9.8 2, 3

Imaging Strategy

• CT abdomen and pelvis with IV contrast is the recommended imaging modality for adults with suspected appendicitis, achieving sensitivity of 96-100% and specificity of 93-95% 1, 2, 4
• IV contrast alone is sufficient and strongly preferred—oral contrast is unnecessary and delays diagnosis 2
• CT identifies complicated appendicitis features: extraluminal appendicolith, abscess, extraluminal air, appendiceal wall enhancement defect, and periappendiceal fat stranding 2

Special Population Modifications:

• Children/adolescents: Ultrasound first-line (sensitivity 76%, specificity 95%) to avoid radiation, followed by CT if inconclusive 1, 2
• Pregnant patients: Ultrasound first, then MRI without IV contrast if inconclusive (sensitivity 94%, specificity 96%)—avoid CT 1, 2
• Elderly patients: CT with IV contrast strongly recommended due to higher rates of complicated appendicitis and mortality 2

Definitive Management

Antibiotic Therapy

• Initiate broad-spectrum antibiotics immediately once appendicitis is diagnosed or strongly suspected, covering aerobic gram-negative organisms and anaerobes 1, 4, 5
• Appropriate regimens include piperacillin-tazobactam monotherapy or combination therapy with cephalosporins or fluoroquinolones plus metronidazole 5
• For critically ill patients with healthcare-associated infections, consider meropenem 1g every 8 hours, doripenem 500mg every 8 hours, or imipenem/cilastatin 1g every 8 hours 1

Surgical Intervention

• Appendectomy remains the treatment of choice and should be performed as soon as reasonably feasible once diagnosis is established 1, 4, 5
• Both laparoscopic and open appendectomy are acceptable approaches, with laparoscopic preferred in most cases 1
• Surgery achieves approximately 91% treatment success compared to antibiotics 6

Management of Complicated Disease

• For periappendiceal abscess, percutaneous image-guided drainage is appropriate when available, combined with antibiotics 1
• When percutaneous drainage is unavailable, proceed directly to surgery 1
• Hartmann's procedure may be necessary for diffuse peritonitis in critically ill patients 1

Antibiotic-Only Strategy Considerations

An antibiotics-first approach may be discussed only in highly selected patients with CT-confirmed uncomplicated appendicitis who strongly prefer to avoid surgery, but this carries significant limitations: 5, 6

• Approximately 70% initial success rate, but only two-thirds avoid surgery within one year 5, 6
• 30.7% require appendectomy within the first year 6
• Higher failure rates (≈40%) with high-risk CT findings: appendicolith, mass effect, or appendiceal diameter >13mm 5
• May increase negative appendectomy rates threefold (RR 3.16) if surgery becomes necessary later 6
• Antibiotics may reduce wound infections but treatment success is 76 per 1000 lower than surgery 6

Contraindications to antibiotics-only approach:

• Appendicolith on imaging 5
• Appendiceal diameter >13mm 5
• Mass effect 5
• Signs of complicated appendicitis (perforation, abscess, gangrene) 1, 5

Follow-Up and Monitoring

• For patients with negative imaging but persistent clinical suspicion, follow-up at 24 hours is mandatory due to low but measurable false-negative rates 1
• For patients with equivocal imaging where appendicitis cannot be confirmed or excluded, careful clinical follow-up is required 1
• In patients not responding to initial treatment after 4-7 days, repeat CT or ultrasound imaging and continue appropriate antimicrobial therapy 1

Critical Pitfalls to Avoid

• Do not rely on clinical examination alone without imaging in intermediate-risk patients—this increases negative appendectomy rates and misses alternative diagnoses 2, 7
• Do not delay imaging to obtain oral contrast—IV contrast alone provides excellent diagnostic accuracy 2
• Do not discharge patients with negative imaging without 24-hour follow-up—false-negative rates exist 1
• Do not offer antibiotics-only treatment without CT confirmation of uncomplicated appendicitis and absence of appendicolith—failure rates approach 40% with high-risk features 5
• Ultrasound accuracy is highly operator-dependent and may incorrectly classify up to half of perforated appendicitis cases as simple 2